Cloning and characterization of a thermostable xylitol dehydrogenase from Rhizobium etli CFN42

An NAD⁺-dependent xylitol dehydrogenase from Rhizobium etli CFN42 (ReXDH) was cloned and overexpressed in Escherichia coli. The DNA sequence analysis revealed an open reading frame of 1,044 bp, capable of encoding a polypeptide of 347 amino acid residues with a calculated molecular mass of 35,858 Da. The ReXDH protein was purified as an active soluble form using GST affinity chromatography. The molecular mass of the purified enzyme was estimated to be ∼34 kDa by sodium dodecyl sulfate–polyacrylamide gel and ∼135 kDa with gel filtration chromatography, suggesting that the enzyme is a homotetramer. Among various polyols, xylitol was the preferred substrate of ReXDH with a K _m = 17.9 mM and k_cat /K _m = 0.5 mM⁻¹ s⁻¹ for xylitol. The enzyme had an optimal pH and temperature of 9.5 and 70 °C, respectively. Heat inactivation studies revealed a half life of the ReXDH at 40 °C of 120 min and a half denaturation temperature (T _1/2) of 53.1 °C. ReXDH showed the highest optimum temperature and thermal stability among the known XDHs. Homology modeling and sequence analysis of ReXDH shed light on the factors contributing to the high thermostability of ReXDH. Although XDHs have been characterized from several other sources, ReXDH is distinguished from other XDHs by its high thermostability.     

Characterization of β-glucosidase from a strain of Penicillium purpurogenum KJS506

A novel β-glucosidase (BGL)-producing strain was isolated and identified as Penicillium purpurogenum KJS506 based on its morphology and internal transcribed spacer (ITS) rDNA gene sequence. When rice straw and corn steep powder were used as carbon and nitrogen sources, respectively, the maximal BGL activity of 12.3 U ml⁻¹, one of the highest levels among BGL-producing microorganisms was observed. The optimum temperature and pH for BGL production were 32 °C and 4, respectively. An extracellular BGL was purified to homogeneity by sequential chromatography of P. purpurogenum culture supernatants, and the purified BGL showed higher activity (V _max = 934 U mg protein^–1) than most BGLs from other sources. The complete ORF of bgl3 was cloned from P. purpurogenum by a modified thermal asymmetric interlaced polymerase chain reaction. The bgl3 gene consists of a 2,571-bp ORF and encodes a putative protein containing 856 amino acids with a calculated molecular mass of 89,624 Da. The putative gene product was identified as a member of glycoside hydrolase family 3. The present results should contribute to improved industrial production of BGL by P. purpurogenum KJS506.     

Purification and characterization of a thermostable xylanase from Fomitopsis pinicola

An extracellular xylanase was purified to homogeneity by sequential chromatography of Fomitopsis pinicola culture supernatants on a DEAE-sepharose column, a gel filtration column, and then on a MonoQ column with fast protein liquid chromatography. The relative molecular weight of F. pinicola xylanase was determined to be 58 kDa by sodium dodecylsulfate polyacrylamide gel electrophoresis and by size exclusion chromatography, indicating that the enzyme is a monomer. The hydrolytic activity of the xylanase had a pH optimum of 4.5 and a temperature optimum of 70 degreesC. The enzyme showed t(1/2) value of 33 h at 70 degrees C and catalytic efficiency (k(cat) = 77.4 s?1, k(cat)/K(m) = 22.7 mg/ml/s) for oatspelt xylan. Its internal amino acid sequences showed a significant homology with hydrolases from glycoside hydrolase (GH) family 10, indicating that the F. pinicola xylanase is a member of GH family 10.     

Distress calls of the greater short-nosed fruit bat Cynopterus sphinx activate hypothalamic-pituitary-adrenal (HPA) axis in conspecifics

In a stressful situation, greater short-nosed fruit bats (Cynopterus sphinx) emit audible vocalization either to warn or to inform conspecifics. We examined the effect of distress calls on bats emitting the call as well as the bats receiving the distress signal through analysis of the hypothalamic-pituitary-adrenal axis and catacholaminargic systems. We measured the levels of neurotransmitters [serotonin (5-HT), dopamine (DA), norepinephrine (NE)] and stress hormones [(adrenocorticotropic hormone (ACTH) and corticosterone (CORT)]. Our results showed that distress call emission elevated the level of ACTH and CORT, as well as 5-HT, DA and NE in the amygdala, for both the call emitting bat and the responding bat. Subsequently, we observed increased activity of glucocorticoid receptor and its steroid receptor co-activator (SRC-1). An expression of SRC-1 was up-regulated in the distress call emitter only, whereas it was at a similar level in both the call responder and silent bats. These findings suggest that bats emitting distress calls and also bats responding to such calls have similar neurotransmitter expression patterns, and may react similarly in response to stress.     

Allotment of carbon is responsible for disorders in proteins

Sequence stretches in proteins that do not fold into a form are referred as disordered regions. Databases like Disport describe disordered regions in proteins andweb servers like PrDOS and DisEMBL, facilitate the prediction of disordered regions. These studies are often based on residue level features. Here, we describeproteins with disordered regions using carbon content and distributions. The distribution pattern for proteins with disordered regions is different from those that donot show disordered regions.     

Distress call-induced gene expression in the brain of the Indian short-nosed fruit bat, Cynopterus sphinx

Individuals in distress emit audible vocalizations to either warn or inform conspecifics. The Indian short-nosed fruit bat, Cynopterus sphinx, emits distress calls soon after becoming entangled in mist nets, which appear to attract conspecifics. Phase I of these distress calls is longer and louder, and includes a secondary peak, compared to phase II. Activity-dependent expression of egr-1 was examined in free-ranging C. sphinx following the emissions and responses to a distress call. We found that the level of expression of egr-1 was higher in bats that emitted a distress call, in adults that responded, and in pups than in silent bats. Up-regulated cDNA was amplified to identify the target gene (TOE1) of the protein Egr-1. The observed expression pattern Toe1 was similar to that of egr-1. These findings suggest that the neuronal activity related to recognition of a distress call and an auditory feedback mechanism induces the expression of Egr-1. Co-expression of egr-1 with Toe1 may play a role in initial triggering of the genetic mechanism that could be involved in the consolidation or stabilization of distress call memories.     

Antitumor activity of methylan polysaccharide derivatives

Methylan polysaccharide derivatives were prepared by dialkylaminoalkylation and reductive amination followed by quaternization. Their antitumor activity was investigated and a relationship between structure and activity is suggested. For quaternized DEAE-methylan at only 75 μg ml^?1, tumor cell proliferation was suppressed by 58–84% in three cell lines tested in the order Colo < Hela < HepG2.     

Inter retrotransposon based genetic diversity and phylogenetic analysis among the Musa germplasm accessions

In the present investigation, the insertional polymorphisms of retro-elements were studied in the Musa germplasm available at ICAR-NRCB field gene bank using IRAP markers. The maximum number of polymorphic bands were produced by the primer pair Nikita and LTR 6150 (48) followed by LTR 6149 and 3′LTR (47) and minimum of 35 bands were produced by the primer pair Sukkula and LTR 6150. The bands produced were scored as 0 (absent) and 1 (present) and the resultant binary data was subjected to diversity analysis. The dendrogram consisted of two major clusters with members of Eumusa and Rhodochlamys in one indicating their genetic closeness and members of the genus Ensete in another cluster. Results of principal coordinate analysis were congruent to those obtained in hierarchial cluster analysis. The molecular markers used in this study could reveal intra and inter-group diversity among the Musa germplasm accessions with similarity co-efficient ranging from 0.41 to 0.99. IRAP marker system has performed excellently clustering the accessions based on both genomic and subgroup levels. The entire germplasm was found to be robust with no duplications indicating the diverse group of accessions available at ICAR-NRCB field gene bank. It has also exhibited high polymorphism and hence could be effectively used to detect the genetic relatedness among diverse genome of Musa.     

CARBANA: Carbon analysis program forprotein sequences

There are lots of works gone into proteins to understand the nature of proteins. Hydrophobic interaction is the dominant force that drives the proteins to carry out the biochemical reactions in all living system. Carbon is the only element that contributes towards this hydrophobic interaction. Studies find that globular proteins prefer to have 31.45% of carbon for its stability. Taking this as standard, a carbon analysis program has been developed to study the carbon distribution profile of protein sequences. This carbon analysis program has been made available online. This can be accessed at www.rajasekaran.net.in/tools/carbana.html. This new program is hoped to help in identification and development of active sites, study of protein stability, evolutionary understating of proteins, gene identification, ligand binding site identification, and to solve the long-standing problem of protein-protein and protein-DNA interactions.